I know this is an old thread, but I just had to post and tell you it solved a very upsetting problem for me.
I'm using Linux Mint13/Cinnamon 64bit with a Nvidia onboard video controller and an Acer widescreen monitor with the weird 1600x900 aspect ratio. Planeshift wouldn't run properly with any of the screen resolution settings options listed in the planeshift GUI. The Game client kept crashing every time I hit the "play" button and even the update messages that show at start-up of the game client didn't display properly and were unreadable. On my original Mint12 OS planeshift crashed my whole system and the video display never would come up again. (thus the upgrade to Mint13).  After Locating planeshift.cfg in the planeshift folder and editing the entry for screen resolution The game client runs, and the game is displayed properly.   
Thank you!